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I went after a couple of BMs today to learn a few basics. I ran into problems with the language in the discriptions:


The first BM was FA4616. (I don't even know how to make this a hyperlink so that's my first question (Q1), but it's at: http://www.geocaching.com/mark/details.aspx?PID=FA4616


The discription said: "aluminum marker (other than a disk)". My little Magellan Sport Trak Map brought me to within 3-6' of a flagged stake. The location is adjusted so that made sense. There was about an 8" hole with the marker already dug up at the bottom but it was an aluminum disk. Q2 Why was it not something other than a disk?


The disk read "City of Charlotte GPS #102 FEH-L782. The discription doesn't use the name GPS Station M102 until well into the text and then it talks about finding the Azimuth Mark from M102 which made me wonder if FA4616 is M102 or something nearby but altogether different? That's Q3.


To learn something, I tried to find the Azimuth Mark by going south on S.R 3468 for 0.35 miles (as per the discription) but didn't see it. Then I went after FA4507 at: http://www.geocaching.com/mark/details.aspx?PID=FA4507 Then at 3-6' from where the GPS should be for FA4507 I found an aluminum triangle (at least it wasn't a disk this time) marked NC Geodetic Survey with a nail in the middle going into the side pavement. This turned out to be at 0.32 miles from FA4616.


I first concluded that the Azimuth Mark and FA4507 were one and the same. (Perhaps the 0.35 miles is road miles whereas I had measured 0.32 miles on my GPS as the crow flies?) But then in the discription of FA4507 it again talks about how to find the Azimuth Mark from GPS Station M102 as if it were something altogether different. And also it said the Azimuth Mark is stamped 302 but this triangle wasn't. Q4 is could FA4507 be the Azimuth Mark or not?


I haven't logged anything because I'm not sure what I found. If you aren't as confused as I am and have the patience to sort this out with me, I would be most interested in your answers.


Thanks in advance



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I don't know why it is called a "GPS" station, but FA4616 and FA4507 are two different points. Wish I were closer so I could get in on the mystery!


To do a link, use your EDIT/COPY to record the URL of the page to which the link will point. Then, when writing your post, click the 'http:' button at the top of the screen. Paste the link into the line that appears. Next, you will be given the opportunity to type the text you wish to appear in the link.


HINT: For multiple links, open a WORD document and paste links to the page. Then copy from WORD at the appropriate places in your post. Important: Use the "preview post" function to proof your document and to test the link before going live with your post/reply.



(Near Raleigh)

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Neweyess -


Welcome to benchmarking! It can be difficult especially when the descriptions don't seem to make any sense, but trying to solve the 'puzzle' aspect of it can be fun too.


As far as your two marks, FA4507 & FA4616, it seems clear to me that you found FA4507, the azimuth mark. The uncertainty comes from the description of the station, FA4616. A few things should be understood before we disect these questions. First, the term 'marker' can be, and is, interchanged with the terms 'disk', 'station', 'brasscap', 'brassdisk', and even 'tablet'. There are also other regional terms that are used. The term 'tablet' is quite old and not generally used in modern descriptions. The term 'marker' is probably the most modern term of the bunch and usually not found in older descriptions. Second, the phrase '(other than a disk)' is NOT on the original datasheets for either mark, even though it is showing up on the GC.com benchmark pages. Don't worry about it too much. Third, sometimes, the markings on the disks don't match the description, although they are supposed to. Typos happen.


My gut feeling, given what you describe for both marks, is that you found both of them. In the original description for both marks there are multiple ties (distances) to nearby objects. These should be used to verify the position of the mark, not the GPSr. You didn't mention in your post if you checked any ties, but I'll assume that you did. From reading the original descriptions, it is possible that one or both of the marks were originally positioned using survey-grade GPS. The original datasheets state that sites are suitable for GPS observations meaning there's a good chance that they were. Given that your found coordinates for both marks was only 3'-6' off is a strong indicator that you were in the right locations. Going to find the azimuth mark to help verify the station is a good idea - that's what the azimuth mark is there for. Your measurement between both marks closely matches the published distance between the marks. Your measurement of 0.32 miles = 514.990 meters or 1689.600 feet. A difference of only 7.441 feet - well within the error factor of a recreational-grade GPSr.


Now, about your questions...


Question #2 'Why was it not something other than a disk?'

An aluminum marker can be, and often is a disk.


Question #3 '...if FA4616 is M102 or something nearby but altogether different?'

FA4616 IS M102 - M102 is the designation for FA4616. The question should be whether or not you found M102. What is stamped on the disk is not found in the description, only the designation for the disk. It is possible for there to be more stamped on it. If the number '102' is promenently stamped on the mark, it is good evidence that it could be the mark. I would think that it is.


Question #4 'Could FA4507 be the Azimuth Mark or not?'

Similar to question 3: FA4507 IS the azimuth mark - it is its designation. The question should be whether or not you found the azimuth mark. With no stamping, it's hard to say, but the multiple ties to nearby objects and to the possible station M102 indicate that it could be.


To really be sure, if you want to go this route, would be to contact Hobbs and Associates (it looks like they were the setting engineers), or contact Gary Thompson (919-733-3836), or Lewis Lapine (803-896-7700) and request additional information and descriptions.


Go ahead and post notes on the benchmark pages explaining what you found and post any images of the marks you may have there. It would help us help you determine what you found. You can always change your log to a find or no find later.


Oh... Question #1 'I don't even know how to make this a hyperlink...'

To insert a hyperlink into the body of the text, use the handy 'Code Buttons' located just above the window used to type your post. Clicking the button labeled 'http://' will bring up two dialogue boxes; enter the address to your link in the first, and the title to your link in the second.


Hope this helps!


- Kewaneh

Edited by Kewaneh & Shark
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Here is the latest from the NGS Datasheet:












So if you take a small garden shovel, that station may well be at the bottom of that hole you found. This is a station which is put in place by driving a steel rod to refusal. What this means is that there is a stainless steel rod which has lengths that can be attached together. They just keep adding to it and pounding it into the ground until it stops. Refusal means it won't go in the ground any more. Then they attach the disc to the top. There is more to it than that but you get the general idea... I am thinking if you dig a bit, all will be revealed... The garden trowel is the key. This is a HARN station monumented in 1988.

35 03 57.11190(N) 080 43 42.28543(W) D/M/S First order control. Your GPS with that NAD 83 waypoint should point right at it.


Good Luck,



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Neweyess -


My opinion on FA4616 is that you didn't find it, at least that's what I would log: "Didn't Find It".


If you click on "view original datasheet" on the benchmark's page, you will get a window containing what Geocaching originally used to make the benchmark page. On it is the "STAMPING:" keyword (about in the middle of the original datasheet). It says that the stamping is supposed to be: "M102". Not all benchmarks have a STAMPING keyword, but when they do, it's accurate, as far as I've seen (unfortunately, GC.com didn't import the STAMPING information when it exists, probably because it's often the same as the Designation). What you found is stamped with something else, and not "M102". The only similarity is "102", which I think isn't enough to be able to claim a find. I really doubt that the monumenter would've stamped "City of Charlotte GPS #102 FEH-L782" on the disk and "M102" in the subsequent paperwork to NGS. The usual thing for something stamped like what you saw would be:



but it isn't.


The mystery of "aluminum marker (other than a disk)" is a sort-of paraphrasing of the real definition: "Aluminum marker other than a disk included elsewhere in table". The 'original datasheet' said: "A = ALUMINUM MARKER". I'm guessing that GC.com did use the real definition rather than what's on the 'original datasheet', but not exactly. What do I mean by "real definition"? If you go to the GC.com benchmark FAQ page, and at the bottom, click on the link called "specifications". In there, click on the link for "Annex P" (what I call the "Hippopotamus File"). In the Hippopotamus file, go down to A.12 (about 60% of the way down) to the table for Monumentation Code. The definition of code A is there. It could be interepreted as an aluminum type of disk. :D Even though this is a somewhat detailed point here, the Hippopotamus file is worth knowing about and having a look at. :lol:


I would NOT recommend digging in the bottom of the hole where you found a disk to try to find out if there's another disk in there with it. :D

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Thanks to everyone who ventured an opinion for my questions. Now that I have read them all and obtained some additional information elsewhere, I'm going to state my own conclusions. Additionally, I'll try and clear up some confusion from my original post.


First, let’s take FA4507: I returned briefly today to look at the aluminum triangle again. I wanted to see if it was stamped 302 after all and I had somehow missed it. It wasn't but then I noticed a hole a few feet back from the triangle. The triangle was in fact pointing to the hole. At the bottom of the hole was an aluminum disk that was stamped #302.


My conclusion is that the triangle is a marker for the mark. I hadn't found FA4507 yesterday but today I have. The stamping plus the GPS location are enough to convince me. I also conclude that FA4507 is the Azimuth Mark because as was pointed out, that's its designation in the data sheet. The data sheet reads "Designation: 302 AZ MK". The data sheet also says it’s stamped 302. It doesn't say it is stamped 302 AZ MK and it wasn't, but that's a point I want to save for FA4616


So let’s take FA4616 First of all, I did say I found a disk there though that wasn't clear to everyone. There was no need to dig deeper. I already found one. It's designation is "Designation: M 102" but it was stamped #102 not M 102. Well I have found others logged in the file in addition to FA4507 that have a designation that is different from what is stamped. An example is: FA4506. It's designation is "Designation: 299 RM" yet you can see from the photo that it's stamped 299 --not 299 RM. Based on the stamping, the precedents with other Charlotte disks and the GPS location, I conclude that I have found FA4616 as well.


Actually, it wasn't much of an accomplishment because both were flagged so to speak and already dug up.


Finally, I'll venture a theory as to why designations and stamps do not agree in every detail. Disks are made and stamped ahead of time with numbers on them. Later on and depending on their application the locations and not the disks are given designations that provide further information. Thus 302 AZ MK means that disk # 302 is located as an Azimuth Mark. I suspect the M in M 102 refers to something else but I have no idea what it is. Perhaps it just means "mark”? Anyway, these are my own conclusions as a beginner and I welcome any confirming or dissenting opinions.


Thanks again to everyone who read or responded to my original post!



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